Two new species of creagrocercid nematodes parasitic in earthworms, with comments on the phylogenetic affiliations of the Creagrocercidae Baylis, 1943

Abstract

Two new species of the rare nematode family Creagrocercidae from earthworms are described and illustrated. Creagrocercus braziliensis n. sp. is distinguished from the type-species, C. barbatus Baylis, 1943, by: the presence of four cephalic papillae (vs a pair of finger-shaped latero-ventral processes) on the head; larger amphids; a more posterior excretory pore position; a shorter pharynx which is remarkably expanded at the base; the nerve-ring situated just posterior to the base of the pharynx (vs at mid-pharyngeal level); an anal aperture present in the females; anterior ovary and testis reach just into the anterior half of the body (vs closely posterior to the pharynx); equal, similar (vs unequal, dissimilar) spicules; and a prominent, unpaired precloacal papilla in males. Creagrocercus drawidae n. sp. is related to C. barbatus by a similar pharyngeal shape and the presence of a tail ‘hook’, and to C. braziliensis n. sp. by: the lack of finger-shaped processes on the head and the presence of four cephalic papillae; a similar position of the excretory pore; a similar arrangement and length of the reproductive system; the presence of unpaired precloacal papilla in males; similar, almost equal spicules; and the presence of a tail ‘hook’. From both of these species C. drawidae differs by having: a much shorter body and pharynx; larger amphids; a more posterior nerve-ring position; larger and less numerous eggs; greatly inflated (vs flat) vulval lips; shorter spicules; and a smaller caudal ‘hook’. For C. drawidae, the partial sequences of the SSU (18S) rDNA and the D2D3 segment of LSU (28S) rDNA were obtained and subjected to phylogenetic analyses. The phylogenetic affiliations of the Creagrocercidae are discussed.